Pushbutton-controlled overload circuit breaker



1969 .1. ELLENBERGER 3,432,782

PUSHBUTTONCONTROLLED OVERLOAD CIRCUIT BREAKER Filed May 31, 1967 Fig. 1

x 11 19 7O "1/ V15 &; E113???) Fig.5

v /3 a0 5 9 MA [31 w Inventor IAKOB ELLENBERGER BY W ATTORNEY United States Patent 3,432,782 PUSHBUTTON-CONTROLLED OVERLOAD CIRCUIT BREAKER Jakob Ellenberger,

assignor to Firma firm of Germany Filed May 31,

Claims priority,

U.S. Cl. 335-170 Int. Cl. H01h 9/20 Altdorf, near Nuremberg, Germany, Ellenberger & Poensgen G.m.b.H., a

1967, Ser. No. 642,401 application Germany, Aug. 3, 1966,

10 Claims ABSTRACT OF THE DISCLOSURE Summary 0 the invention The present invention relates to an electromagnetic pushbutton-controlled overload circuit breaker which is provided with a switch element which carries the pushbutton and is adapted to be moved by spring force to its circuit-breaking or Off position, and with an electromagnet which may be energized by direct current for electromagnetically releasing the switch element. The known overload circuit breakers of this type have the disadvantage that they are relatively complicated and of considerable dimensions, and that therefore they cannot be employed for printed circuits. It is therefore an object of the present invention to provide a circuit breaker of the above-mentioned type which consists of as few, simple, and easily manufactured parts as possible and is designed so as to be of the smallest possible dimensions and thus adapted to be employed not only for general use but especially also in connection with printed circuits.

For attaining this object, the invention provides that the armature of the electromagnet is secured to or forms a part of a switch element which, in turn, is secured to the pushbutton, and that the core of this magnet which holds the armature in the attracted position and is premagnetized, preferably by a permanent magnet, is provided with a pair of arms which project toward each other and are spaced from each other by an air gap and carry the coil of the electromagnet, the magnetic flux of which is directed opposite to the flux which is produced by the pre'magnetization of the core. The invention thus produces the advantage that, since the armature is held in its attracted position by the premagnetized core of the electromagnet, there is no longer any need for a special, relatively complicated holding mechanism as required in the known overload circuit breakers. If an excess current occurs and reaches a certain predetermined value, for example, of 1.5 I the premagnetization will be compensated by the magnetic field which is produced by the field coil on the core of the magnet so that the armature and thus the switch element will then be released from the magnet core and be moved by the release springs to its off position.

The magnet core may consist of two very simple T- shaped' parts, the crossbars of which extend parallel to each other, while their central arms extending at right angles to the crossbars are directed toward, but are spaced by an air gap from each other and carry the field coil. One of the ends of each of these crossbars may be con- Patented Mar. 11, 1969 nected to the permanent magnet, while the other end may engage upon the armature. The manufacture of the magnet core may be simplified by making each of the T-shaped parts of two equal metal plates, one of which is provided at one end of its crossbar with a connecting extension which is bent at a right angle thereto. The two plates of each T-shaped part are then applied in inverse positions on each other so that the angular extension of one plate faces and is connected to the permanent magnet, while the angular extension of the other plate faces the armature. These angular extensions facing the permanent magnet produce a large surface engagement between the metal plates and the permanent magnet and reduce the magnetic contact resistance to a minimum, while the angular extensions facing the armature insure a good transmission of the magnetic lines of force from the magnet core to the armature.

The flat sides of the two plates of each T-shaped part are applied upon each other so that the two angular extensions on these two plates extend in opposite directions. In order to simplify the assembly of the circuit breaker, the T-shaped parts are simply inserted into corresponding slots in the coil-supporting body. They are then held in a fixed position by means of the permanent magnet upon which their angular extensions engage. The permanent magnet, the field coil, and the T-shaped parts together form a structural unit which may simply 'be inserted into corresponding recesses in the two parts of the housing of the circuit breaker.

The diagonally opposite end portions of the armature upon which the angular extensions of the T-shaped plates do not engage may be provided with spring-holding studs or the like for holding one end of a pair of release qr disconnecting springs in a fixed position, while the other ends of these springs engage upon a projection on the coil support. The armature may be connected to a contact bridge which projects over both ends of the armature and carriers a pair of switch contacts which are adapted to engage with associated fixed contacts.

For protecting the elements of the circuit into which the circuit breaker according to the invention is connected from being overheated, the magnet core or the armature of the circuit breaker may be made partly or entirely of a ferromagnetic material which has a low Curie point. When in the operation of the circuit this Curie point is reached, the magnet core or the armature or the respective parts thereof will lose their magnetic properties so that the armature will then no longer be held in its on position by the magnet core, but be moved together with the contact bridge to its off position by the action of the release springs.

The feaures and advantages of the present invention will become more clearly apparent from the following description thereof which is to be read with reference to the accompanying drawings, in which:

FIGURE 1 shows an elevation of the overload circuit breaker according to the invention from which one part of the housing is removed;

FIGURE 2 shows a cross section which is taken along the line II--II of FIGURE 1 but with the housing in the closed position;

FIGURE 3 shows a cross section which is taken along the line III-III of FIGURE 1, likewise in the closed position of the housing; 1

FIGURE 4 shows a perspective view of the elements of the magnetic circuit of the overload circuit breaker according to FIGURE 1; while FIGURE 5 shows a side view of the magnetic circuit elements and indicates the magnetic fluxes therein.

As illustrated in the drawings, the overload circuit breaker according to the invention, comprises a housing which may be made of plastic and consists of two equal )arts 1 and 2 both of which are provided with recesses nto which the individual circuit breaker elements may 3e inserted. The magnet core of the circuit breaker consists of four T-shaped metal plates 3 forming two pairs which are disposed within the same plane. The crossbars 4 of each pair of these plates extend parallel to those of the other pair, their central arms 9 project at right angles from the crossbars 4 toward those of the other pair, and the free ends of the two pairs of arms 5 are spaced from each other by an air gap 6. One end of each crossbar 4 is bent over at a right angle so as to from a connecting member 7. As shown particularly in FIGURES 2 and 4, the flat surfaces of each pair of T-shaped plates 3 engage with each other and the two connecting members 7 of each pair project in opposite directions from its opposite ends. The lower connecting member 7 of each pair of plates 3 is connected to a permanent magnet 8, while the upper connecting member 7 is adapted to engage upon an armature 9. As shown in FIGURE 1, this armature 9 is spaced by an insulating plate 10 from a resilient contact bridge to which it is rigidly secured by a pushbutton 12 of plastic, the lower end of which forms a rivet head 13. Each outer end of contact bridge 11 carrieS a double contact 14 or 15, respectively. When the circuit breaker is in the on position as shown in FIG- URE 1, these double contacts 14 and 15 are in engagement with fixed contacts 16 and 17, while in the off position the double contacts 14 and 15 engage with two other fixed contacts 18 and 19. As shown in FIGURES 2 and 3, these fixed contacts 16 to 19 are provided in the form of pins, the thinner end portions 20 of which project equally from the housing part 1 and may be soldered to the respective connections of a printed circuit.

Plates 3 are located within slots 21' in a coil support 21 which is made of a rectangular shape and fits tightly into the rectangular recesses 1' and 2' in the two parts 1 and 2 of the housing. Upon this coil support 21 a field coil 22 is wound, the ends 23 and 24 of which are electrically connected to the two terminal pins 25 and 26. These pins 25 and 26 are designed like the contacts 16 to 19 and each of them is likewise provided with a thinner end portion 20 which projects from the hous- Armature 9 is acted upon by two release or disconnecting springs 27 which are located adjacent to the opposite corners of the rectangular armature 9 where the lower side of the armature 9 is provided with a pair of studs 28, as shown in FIGURE 1, which prevent the upper ends of the release springs 27 from shifting laterally. The lower ends of springs 27 rest on a projection 28' on the coil support 21.

The mode of operation of the overload circuit breaker as above described is as follows.

As indicated in FIGURE 5, the magnetic flux 29 of the permanent magnet 8 extends through the crossbars 4 of the T-shaped plates 3 and the armature 9 because of the large magnetic resistance of the air gap 6. The magnetic fluxes 30 and 31 which are prouced by coil 22 are closed by the armature 9 and the permanent magnet 8. The magnetic fluxes 29 and 31 flow in the same direction, whereas the magnetic flux 30 flows in the opposite direction to and opposes the flux 29 of magnet 8. At a flow of a normal current I the holding force of magnet 8 which is reduced by the magnetic flux 30 will be greater than the force of the release springs 27. If, however, the current flowing in the coil 22 reaches a certain predetermined value, for example, a value of 1.5 I the magnetic flux 29 of magnet 8 will be weakened to such an extent by the magnetic flux 30 that the release springs 27 will lift the armature 9 from the connecting parts 7 of plates 3. The contacts 14 and 15 on contact bridge 11 are thereby separated from the fixed contacts 16 and 17 and engage with the fixed contacts 18 and 19. The circuit breaker may then again be switched on to its position as shown in FIGURE 1 by depressing the pushbutton 12.

Plates 3 or the armature 9 may consist either partly or entirely of a ferromagnetic material of a low Curie point which may amount, for example, to 60 or 70. When reaching this temperature, the armature 9 or the plates 3 or the respective parts thereof will lose their magnetic conductivity so that, when the circuit breaker is in the on position according to FIGURE 1, the armature 9 will be released from the magnet core 3 and be moved together with the contact bridge to its off position by the action of the release springs 27.

Both parts 1 and 2 of the housing are provided with a stud 32 and a corresponding socket bore 33 so that, when the two housing parts are applied on each other, the two studs 32 engage into the associated socket bores 33. The two housing parts 1 and 2 may then be secured to each other, for example, by gluing or welding.

All of the contact or terminal pins 16, 1'7, 18, 19, 25, and 26 are integral with their pin-shaped ends 20 and of an identical shape and made, for example, of brass, and at their contact points they are provided with flat surfaces.

Although my invention has been illustrated and described with reference to the preferred embodiment thereof, I wish to have it understood that it is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

Having thus claim is:

1. An overload circuit breaker having a housing, a switch element within said housing having an on position and an off position, a pushbutton projecting through the outside of said housing for moving said switch element to said on position, an electromagnet in said housing adapted to be energized by direct current for electromagnetically releasing said switch element from said on position, and spring means attached to said switch element for moving said released switch element to said off position, wherein said electromagnet comprises an armature forming said switch element and having contacts thereon, a magnet core for attracting and releasing said armature and being premagnetized so as to have a magnetic flux flowing in one direction and having a pair of arms directed toward but spaced by an air gap from each other, and a field coil mounted on each of said arms and adapted to produce a magnetic flux in said core flowing in the opposite direction to said prema-gnetized flux.

2. An overload circuit breaker as defined in claim 1, further comprising a permanent magnet connected to said magnet core for premagnetizing the same.

3. An overload circuit breaker as defined in claim 2, wherein said magnet core comprises a pair of T-shaped parts having crossbars extending parallel to each other and central arms on said crossbars and extending at right angles thereto toward each other and their free ends being spaced from each other by said air gap, said arms carrying said field coil, one of the outer ends of each of said crossbars engaging with said permanent magnet and the other outer end being adapted to engage with said armature.

4. An overload circuit breaker as defined in claim 3, wherein each of said T-shaped parts consists of two equal metal plates, one of said plates having a connecting member extending at a right angel from one end of its cross bar.

5. An overload circuit breaker as defined in claim 4, wherein said two plates of each of said T-shaped parts are disposed inversely to each other so that the connecting member on one of said plates faces the permanent magnet and the connecting member of the other plate faces said armature.

6. An overload circuit breaker as defined in claim 5, wherein the two connecting members of each of said T-shaped parts facing said permanent magnet and said armature respectively, extend in opposite directions from the opposite ends of said T-shaped part, the sides of said two plates of each of said T-shaped parts opposite to the fully disclosed my invention, what I sides from which said connecting members project engaging upon each other.

7. An overload circuit breaker as defined in claim 6, further comprising a coil support carrying said field coil on said arms, said lcoil support having slots into which said T-shaped parts are inserted.

8. An overload circuit breaker as defined in claim 7, wherein said spring means comprise a pair of compression springs each having one end engaging upon a part of said coil support and another end engaging upon a part of said armature is free of engagement with said connecting members facing said armature, and means on said armature for holding said other ends of said springs in a substantially fixed position.

9. An overload circuit breaker as defined in claim 1, wherein said switch element comprises an armature plate adapted to engage with and disengage from said magnet core, and a contact bridge projecting at both ends over said armature plate and secured by said pushbutton to said armature plate, said contacts being secured to said ends of said contact bridge.

10. An overload circuit breaker as defined in claim 1, wherein at least a part of said magnet core and armature consists of a ferromagnetic material having a low Curie point.

References Cited FOREIGN PATENTS 8/1960 France.

" BERNARD A. GILHEANY, Primary Examiner.

HAROLD BROOME, Assistant Examiner.

US. Cl. X.R. 

